Automatic pilot for dirigible craft



Aug. 13, 1940. 1'. w. KENYONET AL 2210,

AUTQMATIC PILOT FOR DIRIGIBLE CR4?! Original Filed April 5, 1938 {Sheets-Sheet 1 n R m mm hl lfnwon mm J? Znlvo ATTORNEY I mm B E 8 gm T020000: 8; 5% THE I R l .Nm Rm Aug. 13, 1940 T. w. KENYONiET AL 9 v AUTOMATIC PILOT FOR DIRIGIBLE CRAFT Original Filed April 5, 1938 2 Sheets-Sheet 2 E TO AIRVPUMP IN'VENTORS 711500025 ME/YYfl W STEPHEN Jf Znlvo El TTORNEY 1 Patented Aug. 13, 1940' i j UNITED STATES PATENT OFFICE AUTOMATIC PILOT FOR DIR-IGIBLE CRAFT I Theodore W. Kenyon, Huntington, and Stephen J. Zand, Forest Hills, N. Y., assignors to Sperry Gyroscope Company, Inc., Brooklyn, N. Y., a corporation oi New York Application April 5, 1938, Serial No. 200,084

Renewed June 20, 1939 17 Claims. (Cl. 244- 18) This invention relates to automatic pilots for mally used only as an indicator on aircraft. The dirigible craft, and is especially adapted for airstandard gyroscopic artificial horizon assumes the planes. Our invention has special application to form shown in Fig. 1, the same being enclosed the type of automatic pilot shown in our prior within a casing I, from which air is normally cor.-

5 application for Reactive servo system for autotlnuously pumped through a pipe 2. Said gyromatic pilots, Serial No. 149,136, filed June 19, scope is shown as in the form of a rotor bearing 1937, although it is likewise applicable to other casing 3, carrying the rotor on a normally vertypes of automatic pilots, especially of the fluid tlcal spinning axis 4, the casing being trunnioned operated type. on transverse axis 5 in gimbal ring 6, the gimbal In the system shown in our aforesaid applicaring bein in turn ltlllnnioned 0n fore and aft tion, a gyroscope responsive to angular velocity axis 1 in the casin -v e o o nd a of the craft is used in addition to the positional 0 Such a gy osc pe is usually in' the form of a gyroscope for controlling the signal to the relay horizontal bar 8 visible through the front window valve, so as to discontinue the control signal or 9 and mounted o rearwardly extending arm impulse before the airplane has returned to its s m C p e y described in'the Prior Patent original position, in order to prevent hunting to B. G. Carlson #1,982,636, dated December 4, or unquenched oscillations of the craft due to its 934. f A driven gyro fl is angular momentum. moved up and down on pitching of the craft According to our present invention, we elimby a crank pin II ontrunnion 5 on the rotor I inate the necessity for employing this extra gyrocasing, extending through the gimbal ring, while scope about each axis of control, or at least about the said bar, being pivoted by a pin 12 on the the two horizontalaxes of control, as is usually gimbal ring, rocks laterally therewith 011 I011 secured from a gyro vertical or artificial horizon, bank of the craft.

and we employ instead a simple dlfierential pres- For picking off the banking control, we have .25 sure follow-back or shut-ofi device operable with Shown & valve member in the form of a substana time lag, which slowly removes .the primary tially semicircular segment l3 mounted on a signal before the airplane returns to its original shaft 14' journalled at the rear and outside of position, in other words, before it would othercasing l in beei9 and Which is turned. wise be removed by the return movement of the from the gyro c p y e s o a ea mounted airplane. 1 on shaft l4, whichgear meshes with a gear IS A further object of' our invention is to imsecured to the extension 11 from the gimbal ring prove the differential air pick-offs from the gyro 6. Said segment i3 is enclosed in a housin vertical or artificial horizon so that a standard casing is which iS l t ly mounted a out form of horizon may be employed and the pickthe axis of shaft M, as by means of bearings I9 off devices both mounted at the rear of the casand 20'.

ing of the horizon gyroscope. By this means the Ports 2| a d a e P o d in the eppesite construction is simplified and standardized and Sides of Sa d casing, which are normally Closed the size and weight reduced, to an equal, extent by the segment 13 (see Fig. 2). Referring to the drawings: The interior of casing 18 is preferably not c0n-- 40 Fig. 1 is a diagrammatic view of our control nected with the interior'of the casing ut a as applied to one axis of the airplane (in this insepar ex u p p 3 i c nn c ed therewith stance the fore and aftaxis or aileron control) so that air is continuously exhausted therefrom parts of the gyroscope being shown in horizontal at a-eo sta t atet w e ly be Seen, r

section, the relay valve in vertical section, and 0 e.- h tup n l t v tilting f the craft and the control surface and servo motor on a greatly gyroscope, Ports 2| and 22 Will. be difierentielly reduced scale as compared to the other parts of cov d, resulting n a lfise p u in one the figure. pipe 24 leading to relayvalve 25, and in a fall Fig. 2 is a section of one of the pick-01f valves in pressure in the oth r p p 6 l ad to s of Fig. 1, taken approin'mately on line 2-2 of valve,'the pipes being shown asconnected to dia- Fig. 1, the follow-back differential pressure device phragmed chambers 31 and 38 at opposite ends adjacent thereto also being in section. of said relay valve to differentially displace the Fig. 3 is a detail, in elevation, of the linkage for piston valve 21 thereof which controls the flow of controlling the other pick-off valve in Flg. '1. oil to the main servo cylinder 29, as more com- We have shown our inventionas applied to a pletely described in our prior application No.

standard gyroscopic horizon or gyro vertical, nor- 149,136.

chamber'or cylinder: 30 having atdiaphragm 3| or otherp'iston device dividing the chamber into;

two compartments, each of which has an adjustable leak 1| or 12. One side of said chamber;

is connected to the pipe 24through a variable throttle valve 32 and pipe 33, while the other side is connected to the pipe 26 through throttle valve 35 and pipe ,34. are provided somewhere infthe'pipe connections 24 and 26 or in the chambers 31 and 38 of the relay valve, so that continuous air flow is produced through both pipes unless one of ports 2| or,

22 is closed, the pressure in the pipes being inversely proportional to the relative amount of opening, of ports 2! and 22.

Diaphragm 3| is connected to the housing l8 as by means of piston rod 39 and lever 4|, the forked end of which is engaged by a pin 40 on casing l8, so that movement of the diaphragm will rotate the housing l8 around the member l3, thereby operating to restore'the ports to the balanced position, the housing [8 being normally centralized by opposed springs 42.

In operation, as long as the aircraft maintains its proper attitude no relative movement occurs between the two parts of the pick-ofi valve |3I8. Hence there is no pressure difference in pipes 24 and 26 or on. the two sides of the diaphragm 3i. pressed, the casing I3 will be rotated with respect to the segment 13, resulting in an immediate differential pressure being established in the pipes 24 and 26 to move the piston 21 of the relay valve 25. As soon as this occurs, however, pressure will start to build up in one side of the chamber 30 and to fall in the other side at a rate dependent on the adjustment of the throttle valves 32 and 35, so that after a time determined in accordance with the time constant of the device for the particular setting of the throttle valve at the time,-

which valves in turn are set in accordance with the characteristic period of the craft, depending on the moment of inertia and most used velocity of the craft, the diaphragm will move the casing l8 in a direction to reduce the signal and, in fact, to completely remove or even reverse tl.-

signal before the airplane returns to its original attitude, thus eflfectively dampi .g oscillations of the craft.

The relative effectiveness of applicants device as a damper may be said to depend primarily on the relative time lag interposed between the initiatior. of the primary signal and the shutting off of the same by the device as compared to the angular rate of movement or period of the craft at the time. In other words, an out-of-phase relation is introduced by the device between the primary impulse and the follow-up action of the device, which, for any given valve setting, is a minimum for very slow movements of the craft and increased for more rapid movements, which is of course desirable. Our invention also has the effect of desensitizing the pick-oil device due to its follow-up action, which is the complement of its action as a damper. In case the airplane is turning very slowly. for instance, and the valves are not too far closed, the diaphragm will move practically in phase with the primary signal or the rudder and therefore will have its maximum efiect as a desensitizer, since it tends to shut off and thereby reduce the signal almost immediately. On the other hand, under these circumstances it has its minimum effect as a damper,

Assuming that one wing is desince it operates almost in phase with the signal.

the ,valves. restricted, the diflerential signal changes muchmore' rapidly than the pressure can change on the two sides of the bellows 3|, so

5 that the effect of the device as a desensitizer is greatly reduced but its effect as a damper or anticipator is increased. Our invention therefore acts 'somewhat as a rate device or as a rate gyro- Variable leaks 36 and 36 scope, which it displaces or supplements, and its proportional effect on the system is readily ad- 'justed by varying the opening of the needle valves trol in addition to its function as an anticipator or damper.

The relay valve is shown as-equipped with the hydraulic follow-back system described in our aforesaid application, by which the necessity for follow-back cables from the control surface is eliminated. Oil pressure is supplied to the valve from pipe 45, said pipe being connected to a pair of ports 46 and 41 in the wall of the cylinder bore 48. Alternative outlet ports are shown at 49 and 50, leading through pipes 49' and 50' to opposite ends of the servo cylinder 29. Piston valve 21 is shown as having three piston 5i, 5| and 52. In the position shown in Fig. 1, both intake ports are closed and the common outlet port 53 to the sump is also closed, but it will readily be. seen that movement of the piston to the left will connect the intake port 46 to port 49 and the outlet port 53 to port 59, while movement in the opposite direction will connect intake port 41 to port 50 and outlet port 53 to port 49.

56 with the return passage 58, which is connected to the return port 53. Neither balls 55 nor restricted orifices 51 are, however, necessary for the simplest design. This construction results in limiting the rudder throw by the dynamic air pressure thereon, so that the rudder movement is proportional to both course deviation and, inversely, to air speed, and it cooperates with the follow-back device at the gyroscope previously described, in producing a very sensitive control but without unwanted oscillations.

As pointed out in our prior application Ser. No. 149,136, n our servo motor system the oil pressure supplied to the servo motor is at al times proportional to the effective differential air pressure supplied thereto. Therefore, by varying the air pressure, the operating oil pressure may be changed at will, and hence the amount of rudder movement may be regulated at will since in our system the rudder moves until the back pressure of the air thereon equals the pressure of the oil. A convenient means of regulating the air pressure is by inserting a throttle valve in the air line leading to the vacuum pump. We have shown such a valve in the pipe 23 and a similar valve 9| in the pipe connection to the piston valve 69. By adjusting these valves, the pressure supplied to the chambers 31, 38 is varied, and therefore the pressure supplied to the servo motor is varied since the moment the oil pressure sup- 7 plied to the servo motor rises slightly above the The control about the pitch axis of the craft may be identical in principle to that already described with respect to the bank axis. In order, however, to place both pick-offs at the rear of the gyro casing without changing materially the construction of the standard gyroscope, we use a piston or slide valve arrangement as the pitch pick-off means, having the movable member in the form 'of a piston valve 60 and a small piston rod 6| which slides through a hole in the center of the trunnion 1 and abuts at its rear end against an arm 62 depending from a shaft 63 pivoted on gimbal ring 6 (Fig. 3). Said shaft is provided with a second depending arm 65, against which normal] 1 bears the end of a small rocker arm 66 secured to the pin or shaft l2 which carries the horizon arm I0. Therefore, if the horizon arm is moved up and down by the crank pin l I engaging a slot therein, the shaft l2 will be rocked and move the arm 65 in a counter-clock- Wise direction, the opposite movement of the arm being brought about by a light spring 64, which maintains the two arms in contact. Said spring, however, exerts no force'on the gyroscope because it is counterbalanced by a second. spring 61 ex- 35 and adjustable leaks 1i and 12' are provided.

The sleeve or cylinder 68 is provided with the usual ports 18 cooperating with the several pistons 19 on the piston valve 60 in the usual man ner. The ports 18 merge into elongated annular channels 80 in the outer surface of the sleeve 68 which register with ports 8| in the stationary housing 82 regardless of the limited movement of the sleeve. In this instance the diaphragm is connected to the sleeve 68 through a lever 13 and link 14, the lever being shown as pivoted on the sleeve and having a spring 15 behind the same.

Manual adjustment of the angle of pitch may be secured by turning the thumb screw 16, which also moves the lever 13 through a pin and slot connection Tl. For the manual control of the banking, there is shown a similar thumb screw,

1 18 which moves laterally a cam 19 to rock the lever 4| for adjusting the position of the casing l8.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made connected to the ports in said housing, and a delayed action difierential pressure device slowly responsive to the effective pressure supplied to the relay, and causing said other member to slowly follow the first mentioned member to reduce or take off the signal to the relay.

2. In an automatic pilot having a position maintaining instrument, a differential air flow pick-01f means including a valve member and ported housing, said valve being movable' with said instrument, a relay valve connected to the ports in said housing, and a delayed action difl'erential pressure device slowly responsive to said ports and relay through restricted orifices, and difierentially connected to said pick-off means to reduce or take off the signal'to said'relay.

3. In an automatic pilot for aircraft having position maintaining means, a differential air fiow pick-ofl' valve device thereat, a pneumatichydraulic relay valve actuated from the air flow pressure created by said device, a delayed action differential air pressure device slowly subject to the effective air pressure supplied to said relay for restoring said device to its neutral position, a hydraulic servo motoroontrolled by said relay, and means associated .with said relay subject to the pressure in said servo motor for restoring said relay to neutral position.

- 4. In an automatic pilot having a position maintaining instrument, a fluid pressure pick-off means including a valve member and ported housing, one of which is movable with said instrument, a fluid pressure device connected to the ports in said housing, a delayed action differential pressure. device in the connections between said ports and fluid pressure device, and causing said housing to slowly follow said valve member to reduce or take 011 the signal to the fluid pressure device, and manual means also for altering the position of said housing to change the attitude of the craft.

5. An air fiow pick-off for both axes of a gyroscopic artificial horizon mounted within its casing with its major axis fore and aft and its minor axis athwartships, and having a horizon bar, a rotary valve onthe back of said casing for controlling the actuation of the ailerons, and having a shaft projecting through the casing rotated by relative movements of the gyroscope about said fore and aft axis, a piston valve also on the back of said casing having a piston rod projecting with said casing along said fore and aft axis, and means connecting said bar and rod for axially sliding said rodupon relative up and down movement of said bar.

6; An air flow pick-ofi for both axes of a gyroscopic artificial horizon mounted within its casing with its major axis fore and aft and its minor axis athwartships, a rotary valve on the back of said casing for actuating the ailerons, and having a shaft projecting through the casing rotated by relative movements of the gyroscope about said fore and aft axis, a piston valve also on the back of said casing having a piston rod projecting with said casing along said fore and aft axis, and means for axially sliding said rod upon relative movements of the gyroscope about its athwartship axis.

7. An air fiow pick-off for a sensitive position said arm and piston to slide the latter, said housing having ports for differentially varying the air pressure to a servo motor.

8. An air flow pick-01f for gyroscopes as claimed bar, a piston valve on the back of said casing having a piston rod projecting within'said casing along said fore and aft axis, means connecting said bar and rod for axially sliding said rod upon relative up and down movement of said bar, a.

ported sleeve for said piston rod, and manual means for adjusting said sleeve to alter the angle of attack of the craft.

10. In a fluid pressure automatic pilot for aircraft, a control instrument, a difierential air flow pick-off thereat, fluid pressure servo means for controlling a control surface of the craft, and a relay valve between said servo means and pick-01f subject both to the difierential pressure created by said pick-on and thecounter fluid pressure in Sa d servo means, whereby the effective pressure supplied to the servo means may be adjusted by varying the effective air fiow pressure.

11. In a fluid pressure automatic pilot for aircraft, a control instrument, a differential air flow pick-off thereat, fluid pressure servo means for controlling a control surface of the craft, a relay valve between said serv'o means and pick-oil subject both to the differential pressure created by said pick-ofi and the counter fluid pressure in said servo means, and an adjustable valve in the air supply, whereby the effective pressure supplied to 13.- In an automatic pilot having a position maintaining instrument, a differential air flow pick-oil? means thereon giving alon'e diflerential air pressure signals proportional to displacement,

and a slow acting device for reducing the effective displacement at said pick-ofl, including a chamber having a movable wall connected to said pick-oil and connected through restrictions .to said signals, whereby the signal variesv with both displacement and rate of change of displacement.

14. In an automatic pilot having a position maintaining instrument, a difl'erential air flow pick-oil means creating a. differential signal presthe ports in said housing member, and a delayed action difierential pressure device in the connections between said ports and relay, and causing the other of 'said members to slowly follow the first mentioned member to reduce or take oil the signal to the relay.

16. In an automatic pilot having a position maintaining instrument, a differential air flow pick-off means creating a diflerential signal pressure in two pipe connections in response to relative turning of said instrument and craft, arelay connected to said connections to be adjusted by said signal, a second differential pressure device connected to said connections through restricted orifices, and a follow-back connection between said second device and said pick-off means operating out of phase with its primary movements an amount varying with the rate of change of differential pressure in said pipes.

17. In a fluid pressure automatic pilot for aircraft, a control instrument, a source of air under pressure, a. differential air flow pick-oi! thereat,

hydraulic servo means for controlling a control surface of the craft, a relay valve between said servo means and pick-ofi subject both to the difierential pressure created by said pick-oi! and the counter fluid pressure in said servo means, and means for varying the eflective air pressure, whereby the hydraulic pressure supplied ,to the servo means may be adjusted indirectly.

THEODORE W. KENYON. STEPHEN J. ZAND. 

